Grundfos ALLDOS KM 251 - Combined Overpressure and Degassing Valve; Diaphragm Protection System AMS; Double Diaphragm System; Diaphragm Breakage Signal (Optional)

KM 251 en
16 15.720148-V1.0
1p Motor
2p Worm gearing
3p Eccentric
5p Sliding plug
6p Piston
M combined overpressure and degassing valve
E Degassing valve
9p Diaphragm protection valve (AMS)
Q Dosing diaphragm
2 Dosing head
3a Suction valve
3b Pressure valve
L Stroke adjustment button
F Aeration screw with oil-level gauge
4.1.1 Combined overpressure and degassing valve
The combined overpressure and degassing valve (M) opens if there is an excessively
high build-up of pressure in the dosing system and provokes the constant degassing of
the hydraulic medium.
4.1.2 Diaphragm protection system AMS
The diaphragm protection system AMS (9p) has a keypad, which is connected to the
dosing diaphragm. The dosing diaphragm oscillates freely in the dosing head and cannot
be overstretched due to a fault in the dosing system, since the diaphragm protection valve
closes if a fault like this occurs.
4.1.3 Double diaphragm system / Diaphragm breakage signal (optional)
General
The piston diaphragm and high-tech dosing pumps with drift-free diaphragm breakage
signal are equipped with:
• Dosing head with PTFE double diaphragm system and
• ball check valve with built-in contact manometer
Double diaphragm system
Dosing pumps with a double diaphragm system with no diaphragm breakage signal have
no manometer. In this case the ball check valve is fitted with a locking unit, order No. 541-
013. The valve however can be retrofitted with a contact manometer.
Ball check
In order for the diaphragm breakage signal to work and to protect the diaphragms, the
gap must be fully deaerated. Dosing heads with a double diaphragm are equipped with a
ball check valve (T), to prevent air from flowing back during the filling and deaeration pro-
cess (2u).
Functioning of the diaphragm breakage signal
The check valve and intermediate gap of the diaphragms are filled with a separating
agent (paraffin oil) at the factory and are set in such a way during start-up on the test
stand, that there is always a hydraulically separated equilibrium between the valve and
S Contact manometer
T Ball check
U Connection piece
2) For dosing heads with a
double diaphragm with no con-
tact manometer (no diaphragm
breakage signal), a locking unit
(order number 541-013) is fitted
instead of the contact manome-
ter.
T
5u
4u
3u
2)
U
5s
3u
2u
S
6s